Sleep is an important vital function. Sleep promotes many functions such as restoration of body, repair of tissues, immune regulation, and consolidation of memory. Insomnia is one of the most common complaints in patients with mental health problems. The prevalence of insomnia is higher in elderly than in general population. The reasons could be due to physiological changes in sleep architecture with aging, high medical morbidity, multiple medication, loneliness, and environmental factors causing sleep disturbances. Although insomnia is a common troubling problem in the elderly, only minority seek professional help. Some elderly self-medicate with over-the-counter medications for their sleep problems. These practices lead to serious adverse effects over the long term. There are many myths related to insomnia in elderly. Thus, insomnia in elderly is often under-recognized and under-treated problem. In this article, we review the literature on sleep problems in the elderly and discuss the systematic evaluation of insomnia in the elderly.

Sleep is an essential biological function. Sleep is not equivalent to rest rather brain will be active and subserves many vital functions required for sustainment of life. It promotes restoration of body, conserves energy, repairs the damaged tissues, enhances immunity, and promotes consolidation of memory.[1],[2] As per the International Classification of Sleep Disorders, chronic insomnia is defined as difficulty in initiating or maintaining sleep, despite adequate opportunities to sleep with daytime consequences for 3 months (with a minimum of three times per week).[3] The Diagnostic and Statistical Manual of Mental Disorders 5 also gave similar definition and subtyped insomnia as episodic if the duration is <1 month and as persistent if it is at least 3 months.[4] Sleep disturbances at night are one of the common complaints among the elderly.[5],[6] Many elderly suffer from sleep disturbances due to various etiologies ranging from medical diseases, neurological conditions, psychiatric disorders, primary sleep disorders, psychosocial factors, and environmental factors.[7],[8] The negative consequences range from feeling tired, worsening of chronic medical conditions to precipitating psychiatric illness, and decreasing quality of life.[9],[10],[11] Only a few elderly visit doctor for sleep difficulties alone, and of which a small proportion could reach or be referred to a psychiatrist or sleep specialist.[12] Sleep disturbances are often ignored and under-treated during regular medical consultations in the elderly.[13] Elderly presenting with any sleep disturbances requires meticulous approach to recognizing the underlying etiology with comprehensive evaluation. The objective of this review article is to discuss the burden of insomnia in the elderly, etiology for insomnia, consequences, and evaluation in the elderly.

Literature Search

The articles related to insomnia and elderly were searched in PubMed and Google Scholar websites. A search using terms “insomnia “ combing with other terms “elderly,” “sleep problems,” “epidemiology,” “sleep pattern,” “psychiatry morbidity,” “quality of life,” “medical illness,” “evaluation,” and “management.” We got 275 articles in PubMed and 214 articles in Google Scholar. 107 articles were hand searched which were related to the topic and published in the English language.

Physiological Changes in Sleep Architecture with Aging

There are significant changes in sleep pattern associated with aging. The changes include both quantitative and qualitative. As we know, normal sleep is divided into major types: non-rapid eye movement sleep (NREM) and rapid eye movement sleep (REM) sleep. Using electrophysiological methods, NREM sleep is divided into three stages: Stages 1, 2, and 3. There are increased sympathetic activity during REM sleep and decreased sympathetic activity during NREM sleep. In normal sleep, NREM phase and REM phase alternate every 90 min. As sleep progresses, the NREM sleep duration reduces and REM sleep increases, and finally, one wakes up during REM sleep. Studies reported that there is decrease in total sleep duration with aging. In infants, the total sleep duration is >16 h, and it reduces to 6–8 h in adults.[14] There is little research which says that there is further reduction in sleep in the elderly. Studies have reported that there is a sleep phase advance in the elderly. Elderly go to sleep early and wake up early. Though total sleep duration is not reduced, elderly will have fragmented sleep. What is consistently proven is that there is reduction in sleep efficiency in elderly. Sleep efficiency is the ratio of actual sleep to the total time spent lying in bed. The reasons for reduction in sleep efficiency in the elderly are increased sleep latency, frequent awakenings in the middle of the sleep, and waking up earlier. Few studies have reported that although elderly sleep less during the night time, they compensate by daytime naps. Overall, there might not be a reduction in total sleep duration contrary to popular belief. There was decrease in NREM Stage 3 and REM sleep duration with aging and longer NREM Stage 1 and Stage 2 duration. Among the changes in stages of sleep, significant reduction in slow wave sleep (NREM Stage 3) to the extent of complete absence is reported.[15] The reason for decreased slow wave sleep in the elderly is due to reduced homeostatic pressure which generally promotes and restores lost sleep.[14] There will be increase in both frequency and duration of daytime naps. It will reach a stage when the elderly will not have any sleep during whole night and they fall asleep at dawn and continue to sleep till afternoon. Eventually, it leads to day-night reversal.[16] Understanding the normal physiological changes in sleep in the elderly is important for two reasons. One is to differentiate from sleep disorders and other to reduce the expectations of elderly and adjust to physiological changes associated in late life. There is no much reduction in sleep time with aging and can function with minor adjustments, whereas in insomnia, there is usually reduction in sleep interfering with daily life and became a preoccupation to a patient.[17],[18]

Epidemiology of Insomnia in Elderly

The prevalence of insomnia varies from community setting to hospital setting and depends on the criteria used to diagnose insomnia in the elderly. In the community-based studies, the prevalence of insomnia ranges from 11.6% to 70%.[11],[19],[20],[21],[22] The prevalence of insomnia in the hospital elderly sample ranges from 23% to 27%.[23],[24]

The prevalence of insomnia in an institutional setting is higher compared to community-dwelling elderly. In a study by Henderson et al. on insomnia in elderly, they reported 12% in institutional residents compared to 16% in community living elderly. Despite the low prevalence of insomnia in institutional residents, 40% of them were taking hypnotic compared to 15% in community living elderly.[25] A prospective, observational study was done by Fung et al. on 120 elderly living in assisted living facility using objective and subjective measures of sleep. The study reported that 39% of the elderly were using sedating medication.[26] More often, elderly living in institutional set up have fragmented, disturbed sleep, have more sleep phase advanced, and found to be on sedatives/hypnotics.[27]

In India, there is a paucity of research when it comes to studies related to insomnia in the elderly. The 10/66 study is an important study that looked at the prevalence of elderly insomnia in low- and middle-income countries. The study reported a prevalence of 37.7% and also mentioned a higher prevalence in men compared to women.[28] A cross-sectional study from Northern India assessed insomnia in 304 elderly men and 200 elderly women attending a geriatric clinic reported insomnia in 32% [Table 1].[29]

There are multiple causes for insomnia in elderly. In many elderly, there might be more than one factor implicated in sleep problems. It is useful to understand the common causes of sleep disturbances in elderly. The etiological factors for insomnia can be broadly classified into medical, neurological, and psychiatric conditions and medication-related and primary sleep disorders [Table 2].[30]

A host of medical diseases can cause insomnia. Any condition as simple as fever can cause sleep disturbances. Among medical conditions known to cause insomnia are congestive heart failure, obstructive airway, bronchial asthma, and obstructive sleep apnea. Painful conditions such as osteoarthritis (musculoskeletal conditions) and malignancies that are common in elderly result in sleep disturbances. Medical problems such as diabetes and related polyuria and benign prostate hypertrophy were causes of insomnia in elderly.[31],[32],[33]

Neurological diseases

There are few common neurological conditions known to cause insomnia. Conditions such as REM behavior disorder secondary to synucleopathies, nocturnal seizures, and peripheral neuropathy result in insomnia.[34],[35]

Psychiatric and neuropsychiatric disorders

Insomnia is both seen as a symptom and seen as a disorder. Sleep disturbances are included as the symptom in many psychiatric conditions. In elderly, certain psychiatric conditions are common compared to young and middle-aged. In the elderly, insomnia is commonly associated with depression, anxiety disorder, psychotic disorders, and alcohol use. Insomnia is also a significant problem in elderly with dementia and delirium.[36]

Medications

Elderly due to their multiple medical illnesses will usually be on multiple medications at any time. Medications also contribute to sleep problems. Few common medications known to cause sleep disturbances are dopaminergic drugs, theophylline derivatives, beta-blockers, anticholinergics, glucocorticoids, and diuretics. These are commonly used medications in the elderly.[37]

Idiopathic/primary sleep disorders

There are many types of idiopathic sleep disorders affecting individuals across the lifespan. In elderly, sleep-related breathing disorder, REM sleep behavior disorder (RBD), and restless leg syndrome (RLS)/periodic limb movement disorder (PLMS) are the most common sleep disorders. The prevalence of RLS and PLMS increases with age.[16]

Social and environmental factors

Many elderly have sleep disturbances due to social and environmental factors. Among the psychosocial factors, isolation, poor social support, stress, boredom, lack of physical activity, retirement, and sedentary lifestyle are the important contributors for insomnia. Environmental factors such noise around the sleeping area due to construction or machinery work, lack of proper sleep area, excessive brightness at night, change of place, conversing in social media, and telephone during late hours might also contribute to insomnia.[8],[38]

Consequences of Persistent Insomnia in Elderly

Medical consequences

Chronic insomnia is a risk factor for many medical illnesses. In a cross-sectional study of elderly subjects, a lifetime of history of insomnia was associated with hypertension, heart disease, stroke, diabetes, hip fracture, and cancer.[19],[39] Another cross-sectional study from China assessed for insomnia and medical comorbidity on 3176 elderly. The study reported that significantly higher proportion of elderly with insomnia was found to have hypertension, arrthymia, migraine, and cerebral hemorrhage compared to elderly without insomnia.[40] The 10/66 study also reported higher comorbid physical illness in the elderly with insomnia.[28] In a recently published case–control study from Taiwan, it reported that nearly 51,734 subjects above 20 years were followed and found to have higher prevalence of diabetes, dyslipidemia, hypertension, coronary heart disease, chronic kidney and liver disease.[9] The pathophysiological mechanism for this relation can be explained by chronic inflammation induced by insomnia. The chronic inflammation in turn leads to insulin resistance, metabolic syndrome, and hyperarousal.[41],[42],[43] Insomnia is also known to cause alterations in endocrine systems and sympathetic and parasympathetic activity.[44],[45]

Neurological consequences

Among the neurological illness, insomnia in the elderly is known to increase the risk of dementia. In a retrospective study by Chen et al., on 5693 individuals with insomnia reported higher prevalence of dementia even after adjusting for other medical illness.[46] The study also found that long-term use of hypnotics had twofold increased the risk for dementia.[46] A case–control study from Taiwan reported that primary insomnia in people below 40 years increases the risk of dementia by twofold.[9] A meta-analysis by Shi et al., on insomnia and risk for dementia, included 18 longitudinal studies comprising 246,786 subjects. The study reported that after 9.49 years, 25,849 subjects developed dementia. A subgroup analysis revealed that insomnia increased the risk of Alzheimer's dementia (AD) but not vascular dementia, but people with sleep disordered breathing had higher risk for all-cause dementia, AD, and vascular dementia.[10] Other risk factors for AD were excessive daytime sleep and depression, whereas sleep-related movement's disorder had inconsistent relation.[10]

Mental health

The short-term consequences of insomnia are fatigue, tiredness, lack of refreshness, daytime drowsiness, irritability, and impaired concentration. This will lead to decreased productivity at work, decreased happiness in life, and overall decreased quality of life. Many studies on insomnia in the elderly reported that insomnia increases the risk of depression. In one of the earliest prospective study on elderly from London reported that insomnia increases the risk of depression.[47] A retrospective on California elderly reported significant correlation between insomnia and depression.[48] A study by Perlis et al. studied the risk of depression in 157 elderly and its relation to insomnia over 1-year period using structured clinical interview for DSM-III (SCID). The study reported new-onset depression in 12 subjects, and the odds ratio for depression in elderly with persistent insomnia was 6.86 (95% confidence interval).[49] Another large prospective study from France on 3824 elderly reported that insomnia and excessive daytime sleepiness increases the risk of depressive symptoms with odds ratio of 1.23 and 2.05.[11] Another important disorder where insomnia is implicated as probable risk factor is delirium. The incidence and prevalence of delirium are 25% and 54% in elderly among Indian studies.[50],[51] Studies were done to understand the sleep problems in delirium.[52] There are shared pathophysiological and neurotransmitter imbalances in delirium and insomnia.[53] In a study on intensive care elderly patients, there was found to be an association between reduced sleep and delirium.[54] Another observational study on elderly who underwent knee replacement surgery reported that postoperative delirium is higher in elderly with obstructive sleep apnea (causing insomnia).[55] Insomnia can also increase the risk of mortality in elderly.[56]

Prescription drug dependence

This is not a direct result of insomnia, but a temporary drug solution for insomnia which later becomes dependence. It is very common for the elderly to seek advice from friend and peers for their sleeping difficulties who suggest or share the sleeping pill they are using. Most elderly start using over-the-counter (OTC) sleeping pills occasionally, and over a period of few months, it becomes a regular use. Many elderly will not increase the dose but will keep consuming the pills every day. Few elderly patients will escalate the dose gradually to a point it becomes a compulsive behavior ultimately landing in addiction. Many elderly also receive sleeping pills during their visit to their family physician which will be continued for many years without supervision. Insomnia per se and also use of hypnotic/sedatives increase the risk of falls, cognitive deficits, daytime drowsiness, and the risk of aspiration.[57] The risk of benzodiazepine (BZD) dependence in the elderly is higher with particularly short-acting drugs such as alprazolam and lorazepam.

Misconceptions About Insomnia in Elderly

There are several misconceptions about insomnia in elderly among the general public as well as some of the physicians. Some of the important misconceptions are as follows

Reduced sleep is a normal aging phenomenon

Reduced sleep in elderly is due to lack of any specific reason

Elderly generally sleep during daytime, so they do not sleep at night

Sleep problems in the elderly is a trivial issue

Insomnia in the elderly does not require any specific professional help

Insomnia is elderly just requires OTC prescription for few days

Insomnia in elderly is always due to physical illness

Elderly cannot sleep without sleeping pills.

It is important to create awareness to address the commonly prevailing misconceptions about insomnia.

Evaluation

History

An elderly presenting sleep difficulties requires thorough and detailed evaluation. The following details should be enquired from the patient during the collection of history. About the duration of insomnia, number of days in a week they have sleep difficulties. What exactly are the sleep problems? Whether patient has difficulty in initiating sleep, maintaining the sleep, and awaking up earlier than usual or combination of all. Patient should be asked about their sleeping habits, normal bedtime, sleep duration, and wakeup time. After these initial clarifications, patients should be enquired about medical and surgical conditions, especially conditions known to cause pain, discomfort, breathlessness, or apnea. Patients should be assessed for depressive symptoms, grief, anxiety symptoms, episodes of confusion, and cognitive decline. Collecting history regarding OTC pill use and detail regarding dose and frequency is important. Further, one should enquire about recent life events, geographical changes, any disturbing things nearby patients place. The patient partner should also be included in the assessment either along with patient or alone. The partner should be asked about snoring or brief lasting apnea episode at night. Along with these, any periodic movements of limbs or myoclonic jerks should be enquired. Another common symptoms which a wife or partner can report are enactment of dreams or any motoric excitement which is suggestive of RBD. Less common but should be enquired with sleep partner is sleep talking or sleepwalking (NREM sleep disorders).

Assessment

After the detailed interview of patients, physical examination specifically looking for hypertension, thyroid swelling, neck girth, and oropharyngeal passage is important. Standard subjective and objective scales will help in diagnosing the problem and also quantifying the problem. Sleep quality can be assessed using the Pittsburgh Sleep Quality Index; it assesses the subjective quality of sleep in the last 1 month and available in many translated versions.[58] To assess the daytime sleepiness in the elderly, Epworth Sleepiness Scale is useful which is an 8-item scale assessing the subjective daytime sleepiness.[59] A commonly used screening questionnaire for obstructive sleep apnea (OSA) is STOP-Bang questionnaire which checks for snoring, tiredness, observed apnea, high blood pressure, body mass index, age, neck circumference, and male gender. Each risk factor is given one point each. A score of 2 or more is taken as cut-off for OSA.[60] For the assessment of RLS, International RLS Scale is a valid instrument. It is a self-reported scale with 10 items each scored on a 5-point Likert scale.[61] In few specific patients, polysomnography is indicated for comprehensive evaluation of their sleep problems. Polysomnography is considered the gold standard tool for the assessment of sleep problems.[62] For the assessment of elderly depression, geriatric depression scale is a validated self-reporting screening instrument that can be applied even in office setting.[59]

Management

The management of insomnia in the elderly requires systematic approach, tailored to the specific etiology of insomnia. After thorough evaluation using available history, validated instruments, and relevant investigations, management should be planned. At the end of evaluation, many elderly will have insomnia without any specific physical or neurological etiology. These patients form the majority in physicians or psychiatrist clinic among the insomnia group.

Nonpharmacological interventions

The first step in these patients would be educating about normal sleep architecture and changes in sleep pattern with aging.[63] Identifying the myths of many elderly patients and their family members is very important in understanding their perspective. Later, self-monitoring of the sleep using simple methods such as sleep diary will be beneficial. In sleep diary, patient can record bedtime, sleep onset, how many times he wakes up in the middle, total sleep duration, nightmares, quality of sleep, and also any significant psychosocial events affecting sleep.[64] In many elderly patients, sleep hygiene will suffice if done correctly for adequate duration.[65] Sleep hygiene is set of behaviors and environmental manipulations as a therapy for insomnia. In a meta-analysis of 15 studies, sleep hygiene was found to have small to medium effect size.[66] It was reported that nearly 30% of insomnia patients improve by merely adopting sleep hygiene measures. Community psychoeducation programs directed at community living elderly about normal physiology of sleep, myths about the sleep, and sleep hygiene will be useful as a preventive measure for insomnia in elderly. There are few other psychological interventions which are found to be effective such as stimulus control therapy and sleep restriction. In stimulus control technique, patient is restricted from doing any in bed activities other than sleeping such watching television, using mobile, or reading.[67] In sleep restriction therapy, patient is allowed to sleep in bed only as long as he/she is asleep and should be out of bed when awake. It helps in improving the sleep efficiency.[68] Another effective psychological treatment for insomnia is cognitive behavioral therapy (CBT) which helps in correcting the cognitive distortions and breaking the classical conditioning.[66],[69] In a double-blind randomized controlled trial (RCT) on older adults with chronic insomnia, CBT was found to be affective either alone or in combination with temazepam at 3, 12, and 24 months follow-up.[70] Physical activity is an important, feasible option for insomnia in elderly which can be done with most patients. Physical activity improves sleep, mood, and physical health.[71] In an RCT on elderly with insomnia, aerobic physical activity of 4 days in a week for 16 weeks showed improvement in quality, duration, and efficiency of sleep.[72],[73] Psychoeducation should also include sharing information about common adverse with sedative/hypnotic medication such as cognitive deficits, osteoporosis, falls, fractures, and rebound insomnia when discontinued.

Pharmacological treatments

Medication should be viewed as the last option for the treatment of insomnia in elderly. There are few circumstances where medications are considered or warranted. One is when behavioral and psychological interventions are not available or not feasible in patients such as dementia or delirium. Another is when elderly patient has episode of depression or psychosis having severe sleep disturbances medication can be given for short duration. When elderly have severe insomnia for many years, medication can be given initially until behavioral and psychological interventions take effect. Medication can be also be considered in the elderly with circadian rhythm abnormalities for short duration.[14],[73] There are guidelines for the management of insomnia in elderly such as Clinical Practice Guideline American Academy of Sleep Medicine (AASM),[74] Clinical Practice Guideline from the American College of Physicians (ACP),[75] National Institute for Health and Care Excellence,[76] and Clinical Practice Guidelines-Indian Psychiatric Society.[77]

Basic principles to follow before prescribing a sedative medication are using the lowest effective dose, using medication with shorter half-time to avoid daytime sedation, and using either intermittently or continuously for shorter duration [Table 3].

Trazodone is an antidepressant with hypnotic property. It has sedative action due to action on alpha receptors. It is one of the commonly used medications for insomnia associated with depression and anxiety. It is known to increase the slow wave sleep and increase REM latency.[78] Trazodone was also found to be effective for insomnia in AD patients in an RCT.[79]

Mirtazapine

It is an antidepressant with additional property of sedation at lower doses. Its sedative property is due to antihistamine action. It is found to improve sleep architecture and decrease sleep latency in a patient with depression and insomnia.[80] The recommended dose for insomnia is 7.5–15 mg.[81] Mirtazapine is not ideal choice in patients with cognitive impairment due to its anticholinergic action.

Doxepin

It is a tricyclic antidepressant with sedative property. At low doses, it is useful for the teatment of insomnia in elderly. The recommended dose for insomnia is 3–6 mg.[82],[83]

Miscellaneous

Ramelteon

Ramelteon is the only Food and Drug Administration approved drug for insomnia in the elderly. Its sedative property is due to action at MT1 and MT2 receptors.[84] Few RCTs have shown its efficacy in elderly with insomnia.[85],[86] Contrary to other sedative medication, it will alter the sleep–wake cycle to decrease sleep latency. The recommended dose is 8–16 mg. Ramelteon has fewer adverse effects and less abusive potential. There is no clear guidelines for using ramelteon for chronic insomnia and it was found to have overall minimal effect on insomnia.[87]

Melatonin

Melatonin is hormone released from the pineal gland, which promotes sleep. It helps in correcting sleep–wake cycle. It is used commonly in shift workers or in people with jet lag. It was also found to be effective for insomnia in the elderly and in AD.[88] The recommended dose is 0.5–2 mg for jetlag. It is not recommended for chronic insomnia as per the ACP and AASM guidelines.

Suvorexant

Suvorexant is another medication, which is approved for insomnia. It is an orexin receptor antagonist. Orexin antagonists are peptides in the brain with important role in sleep–wake cycle.[89] It is shown to improve sleep efficiency in insomnia patients in controlled studies.[90],[91] Notable adverse effects are excessive daytime sleepiness, sleep paralysis, falls, and complex sleep-related behaviors.[90] The approved recommended dose is 5–10 mg.[92]

Benzodiazepines

BZD medication is also commonly used by many physicians, which acts on the GABA-A receptor and causes sedation. BZDs are effective in short term, and their long-term use has to be discouraged. They cause reduction in sleep latency, reduced REM sleep, and frequent awakening.[93] Although effective, they can cause tolerance, cognitive deficits, osteoporosis, falls, fractures, and rebound insomnia when discontinued.[94] Among the elderly who were started on BZD, nearly one-third continue their use for long-term.[95] There is a higher risk of developing dependence on this class of drug.[96],[97]

Z-group of drugs

These are known as non-BZD sedatives. They act on omega subclass of BZD receptors. The medication under this class includes zolpidem, zaleplon, and zopiclone. They were introduced to overcome the adverse effects of BZD, and their use increased exponentially.[98],[99] Later, it was found that these drug also have harmful effects especially in the elderly. Commonly reported adverse effects with Z-group of drugs are headache, dizziness, drowsiness, nausea, anterograde amnesia, hallucinations, and unusual night-time behaviors.[100] They should be prescribed only for 4–5 weeks at lower doses.[75] The ACP and AASM guidelines suggested short-term use (4–5 weeks) of these agents. The effect of various hypnotic medications on sleep architecture is shown in [Table 1].[95],[101],[102],[103]

Management of Insomnia in Dementia

Dealing with insomnia is particularly challenging for dementia patients. Few nonpharmacological interventions such as exposure to bright light in the morning and regular physical activity along with sleep hygiene measure were found to be effective for insomnia in demented patients. Medication such as trazodone and ramelteon were found useful. In patients with REM behavioral disorder associated with Parkinson's related dementia low-dose BZD can be used Careful enquiry for affective disorder and treating appropriately will also improve insomnia.[104],[105],[106]

Conclusion

Insomnia is one of the most common troubling symptoms in elderly. It is often incorrectly attributed to aging phenomenon. The prevalence of insomnia varies depending on setting and criteria used, and it is nearly 42% in age group above 65 years.[107] The etiology for insomnia is generally multifactorial in elderly. Although insomnia is a common symptom, it is under recognized and undertreated. Persistent insomnia leads to multiple negative effects ranging from medical diseases, cognitive decline, psychological morbidity, falls, decreased quality of life, and increased mortality. Many elderly do not receive appropriate advice or treatment and seem to self-medicate. Insomnia requires special attention of treating physician, which requires meticulous evaluation considering medical, psychological, and environmental factors contributing to insomnia. Education about normal sleep pattern and sleep hygiene is the first step in the management of insomnia in the elderly. CBT for insomnia is an effective treatment and should be considered before medication. Medication should be considered after weighing the risk and benefit ratio and only for short duration. In cases with persistent insomnia, it is advisable to take help of a sleep specialist or psychiatrist.